Génie électrique
Vibration-based bearing fault diagnosis by an integrated DWT-FFT approach and an adaptive neuro-fuzzy inference system
The rotating machine, which can be subject to breakdowns or dysfunctions in its time-of-use, represents an essential part in the majority of industrial applications. Hence, their reliability, productivity, safety and availability are very important issues that are imposed to increase production with quality assurance as per given specification at a reasonable cost. Furthermore, because the bearing faults are the most frequent and critical defects in rotating machinery that may have a direct influence on the availability of the machine itself and also on those of the surrounding systems, a particular interest is carried in this paper to the analysis and diagnosis of these defects which can appear in the bearing's ball, inner race and outer race with various fault severity and rotating speed. This paper consists of the application of the Discrete Wavelet Transform DWT and Fast Fourier Transform FFT theories to extract the amplitude of the fundamental bearing defect frequencies in the vibration signal from a rotating machine. These parameters will be used by the Adaptive Neural Fuzzy Inference System ANFIS to automate the fault detection and diagnosis process. Experimental results show that the proposed procedure can classify with precision various types of bearing faults according to the fault location and severity. Voir les détails
Mots clés : bearing faults, vibration signal, Fault Diagnosis, ANFIS, DWT, FFT
Diagnosis of the pipeline corrosion due to the inductive interference between high voltage power line and buried pipeline
In this paper, we study the interference between high voltage power transmission line and buried pipeline. The induced voltage onto the pipeline was calculated for the horizontal and the vertical configuration of the power line, the existence of the earth wire, various separation distances between conductors of the power line, and various separation distances between power line and pipeline. This effect results in a corrosion process which we have proposed some solutions. Voir les détails
Mots clés : Power lines, interference, induced voltage, induced current density, pipeline, AC Corrosion .
Desired Closed-Loop Based Self-Tuning Fractional PID Controller for Wind Turbine Speed Control
Lately, fractional PID controller has gained more interests because it involves two more tuning parameters, the fractional order integration and the fractional order differentiation, in their structure. This type of controller has been introduced in the control system theory in a continuous effort to enhance the system control quality performances. In this paper a self-tuning fractional PID controller for wind turbine speed control is proposed. The fractional PID controller’s five parameters are self-tuned as the system dynamics or operating points change using formulas based on adesired closed loop response. A simulation study of the wind turbine speed control has been done to demonstrate and validate the performance and effectiveness of the proposed control scheme. Voir les détails
Mots clés : Fractional PID controller, self-tuning, wind turbine speed control
Analysis and evaluation of the impact of climatic conditions on thephotovoltaic modules performance in the desert environment
The main objective of this study is to investigate the impact of climatic conditions on the performance ofphotovoltaic modules installed in the desert region in south of Algeria. Firstly, the performance ofISOFOTON 100 module under daily weather conditions is evaluated. Next, the effects of partial shadingand accumulation of sand dust for a period of two months on power loss and the current–voltagecharacteristics of photovoltaic modules are examined. Finally, the visual inspection of the degradationof the UDTS 50 modules such as discoloration of encapsulant and delamination show the influence ofhigh temperature and the other climatic factors in the Saharan environment after a long time exposureof more than 10 years observed in the field at the Unit of Research in Renewable energy URERMS Adrar.The performance degradation is also assessed using (I–V and P–V) curves normalized at STC conditioncompared with the nominal STC data given by the manufacturer. The experimental results show thatthe performance parameters such as maximum output current (Imax), maximum output voltage (Vmax),maximum power output (Pmax), open-circuit voltage (Voc), short-circuit current (Isc) and fill factor (FF)of UDTS 50 modules are degraded after these years of exposition. Voir les détails
Mots clés : Photovoltaic module, Performance evaluation, degradation, Desert environment
Propriétés électriques de cellule solaire à base dediSéléniure de Cuivre Indium Galium CuIn(1−x)GaxSe2 (CIGS)
The work of this memory of Magister is a numerical simulation study of electricalcharacteristics of a solar cell and thin-film heterojunction ZnO / CdS (n) / CIGS (p) / Mousing Silvaco software Atlas-2D. The electrical characteristics of current density versusvoltage J (V) under AM1.5 illumination are simulated: the conversion efficiency = 20.1%,the open-circuit voltage Voc = 0.68 V, the current density of short Circuit Jcc = 36.91 mA /cm ² and the form factor FF = 80%. These simulation results are in very good agreement withthose found experimentally. The photovoltaic parameters of the solar cell are studied andanalyzed by the variation of parameters: thickness and doping of CdS and CIGS layers, thecomposition of Galium compared to indium x. It was found that the variation of theparameters of the front-layer (CdS) has generally less significant effects on the electricalcharacteristics of the cell in comparison with the parameters of the absorption layer (CIGS).The simulation results showed that the molar fraction x of the CIGS layer has an optimalvalue around 0.31 corresponding to an energy gap of 1.16 eV, this result is in good agreementwith that found experimentally. A small improvement in the performance of CIGS solar cellwas made by the addition of the window layer ZnO: Al. Voir les détails
Mots clés : Keywords: Numerical simulation -Silvaco- Atlas-2D – CIGS solar cell –solar cell parameters.
Technico-economical Feasibility Study of a PV Power System for a Village
Algeria being enriched with higher level of solar radiation is a prospective candidate for deployment of solar PV systems.The aim of this study is to analyze long-term solar radiation data of Tindouf (South-West of, Algeria to assess the techno-economic feasibility of utilizing PV–battery power system to meet the load of a typical residential building (with annual electrical energy demand of 9490 kWh). The monthly average daily solar global radiation ranges from 3.61 to 7.96 kwh/m 2 . PVSyst and National Renewable Energy Laboratory’s (NREL) Hybrid Optimization Model for Electric Renewable (HOMER) softwares have been employed to respectively carry out the technical and the economical present study. Voir les détails
Mots clés : Algeria, Homer, Net Present Cost, optimum system sizing, PVsyst, PV system.
Formulation of Mumford and Shah problem by level set
The limitations of the active contour based on borders have directed the research towards solutions wherethe contour is built from all the information contained in the image. They are known as region-based active contours. More robust to the noise and less sensitive to the position of the initial curve, the models based on regions have for general principle to develop a curve so that in the convergence, we realize a partition of the image in two homogeneous regions.We obtain two regions because a single curve bounds only two domains in image. The region-based active contours base generally on statistical. Voir les détails
Mots clés : Level set, Mumford-Shah, weld defect
Modeling and Optimal Sizing of a Wind Energy System for the Electrification of an Algerian Territory.
Wind energy is a renewable energy promoting diversification energy independence of our country. So, wind power is probably the most promising sustainable energy resource. This paper makes easy the task of the assessment models of the power systems for a multitude of applications through a mathematical formulation which gives the stages of wind energy conversion system. Many decisions about the configuration of the system should be made, parameters optimized and losses due to wake effect reduced, a task that Homer takes in hand. It simulates the operation of a system by making energy balance calculations for each of the 8,760 hours a year. Voir les détails
Mots clés : Homer, mathematical formulation, wind turbine output power
Impacts of Inductive and Conductive Interference due to High Voltage Power Lines on Metallic Pipelines
The electromagnetic interference caused by power transmission lines to oil and gas buried pipelines is under investigation for many years. Especially during fault conditions, large currents and voltages are induced. Even under normal operating conditions, voltages and currents are induced on the pipeline that may pose danger to working personnel or may accelerate the corrosion of the pipeline’s metal. In this research, the induced voltage in the oil buried pipelines due to the magnetic fields produced by nearby 400kV transmission lines have been computed on normal and fault conditions Voir les détails
Mots clés : AC interference, Induced Voltages, Electric Power Transmission Lines, pipeline, AC Corrosion
An Improved Method for Gear Fault diagnosis
Envelope analysis is especially suitable for fault diagnosis inducing periodic shocks or amplitude modulations such as gears and bearings and has been applied widely for mechanical fault detections over the last few decades. However, a critical limitation of this technique is that it requires a prior knowledge on filtering band. Due to this drawback, detecting machine defects at the incipient stage when defect-characteristic components are weak in amplitude and without a distinctive spectral pattern poses a challenge to the conventional enveloping spectral analysis technique .In order to overcome this limitation, this work gives a new signal processing approach for gear faults diagnosis based on Hilbert Transform (HT) and Fast Fourier Transform (FFT). It is applied on real measurement signals collected from an experimental vibration system. The monitoring results indicate that the proposed method improves the gear faults diagnosis relatively to other common techniques. Voir les détails
Mots clés : Vibration signal Analysis, gear Fault diagnosis, Hilbert Transform (HT), Envelope Analysis (EA), Fast Fourier Transform (FFT).